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Cant Make Head and Tail of: Aftermarket Tow Hitch/Wiring Options for HW 4.0 Cars

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Deaf Paul

Member
Supporting Member
Apr 9, 2023
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Oahu, Hawaii
I've spent the last few days reading dozens of threads on this here and still am at a loss as of to how to best get a new MYP with HW 4.0 to tow so i can get rid of my gas tow vehicle. My MYP is an inventory car that I put a deposit on, so I was unable to add the hitch option. It's due to arrive in a couple of weeks and I'd like to get this squared away sooner rather than later.

A few points to consider for this thread: I do not want to read discussions about crash protection or the safety aspect of towing without tow mode activated so please don't drag those dead horses into this thread.

I do NOT want to lose my FSD by having Tesla install their hitch and activating tow mode for $1,300. This is an absolute last resort.

My second-to-last resort would be to have Tesla install their hitch and NOT activate tow mode if possible. I've seen some posts saying that it's automatically activated when Tesla hooks up their hitch or wiring somehow and not manually activated by the tech. Not sure how accurate that is.

I also see multiple posts saying that Tesla is not yet stocking the necessary parts for towing to be added post-build MY's with HW4.0 for some reason.. Not sure what's different or if this is still the case. I have not taken delivery of my newest MYP so I cannot confirm this in the app.

It seems like the Draw Tite hitch is the aftermarket best option with EcoHitch in 2nd.

However I'm at a loss about the wiring hook-up. Is there a basic trailer 4-wire or 7-wire hook up already in place behind the bumper? If not, where do I find the correct wiring harness to add to the vehicle? A search online has come up with nothing. I've emailed Draw Tite and they have not responded.

If there is already a trailer plug in place, is it active or not? If not, how do I activate it without needing to have Tesla do it?

To make things more complicated, I found a post by @k24a2 stating that Model Y cars made after 2022 are usually missing the Front Left Body controller chip to control/give power to the rear trailer hook up. Does this mean I am stuck going to Tesla only, or can I order just this part from Tesla and add it myself? Tesla puts it down as a 45 minute job. Factory Service Bulletin about this here

However, reading his post carefully:

For cars that are built after 2022.. The Front Left Body controller is missing the chip to control/give power to the rear trailer 13pin plug....

Only way is to upgrade the body controller with the one capable with tow mode...

Attached is the bullitin for body controller upgrade...

I found out this after I bought a after market hitch and trailer plug...

But now I just wired a aftermarket 4pin trailer controller, and wire a 4 pin to 7 pin trailer plug and ran the wires the old ways

Can somebody explain to me as if I were a simple child, what he meant by his last sentence? It sounds like he found an aftermarket controller and wired that to an existing factory 7-pin factory plug that may already be in place behind the bumper in order to use a 4-wire trailer plug? In which case the factory cars come with a 7-wire plug already under the bumper and working? Yea or nay?

-Paul
 
Use the Tesla solution.

When the Tesla solution is installed, a round 8 pin plug is added next to the receiver in the bumper cutout.

FSD is ONLY disabled when the car detects a trailer is connected. Cruise Control is still available. Once the trailer disconnects, you can turn off tow mode.

Not having FSD is a very minor inconvenience while towing, and it may only be that way for the beta software.

I would have suggested that you order the car with the towing package, but since it sounds as if you may already have it, then just order the add-on package.

I really think that you are overthinking and too worried about nothing.

It's pretty simple.

But don't forget to keep the weight limits in mnd.
 
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Use the Tesla solution.

When the Tesla solution is installed, a round 8 pin plug is added next to the receiver in the bumper cutout.

FSD is ONLY disabled when the car detects a trailer is connected. Cruise Control is still available. Once the trailer disconnects, you can turn off tow mode.
I do NOT want to lose my FSD by having Tesla install their hitch and activating tow mode for $1,300. This is an absolute last resort.

Like I said, this is a last resort measure only. I want to retain my FSD 100% so I can use it if I want to while towing. Questions for you:

1. You said "Cruise Control is still available" - What exactly does this entail? Is it like the EAP I have in my other Tesla, or Autopilot like in my wife's tesla? If so, that would make going to the "Tesla Solution" more acceptable as I would still have self-adjusting speed control and lane centering, etc. Can you clarify? I want to make sure I don't end up with nothing, or just a fixed speed primitive cruise control.

So it sounds like there is NOT a plug anywhere on the Model Y for trailers unless one is added? How do I get this part if i were to install an aftermarket hitch? Can I order it from Tesla? Or do aftermarket companies make this harness?

-Paul
 
I don't think that lane centering was there, just cruise control. You have to remember that when a trailer is connected, vision is restricted. And even bike racks can cause the cars to sound alarms because of obstructed cameras. And even if you have an off-brand solution, the rear camera can get upset.

No, without the trailer package, just like most any other car, there's not a plug and not a receiver. Now you can assume that they do have somewhere that they plug the plug into something. But t may require enabling.

Trying to keep FSD on when trailering, while I'd like to do, probably isn't the most prudent at this time. I've driven over 1,000 miles with a boat and it was no big deal.
 
I believe the alarms only go off in reverse, and I won't even know that they're going off because I'm deaf. So I don't care at all about that. 😅

I want to retain assistive driving features, so I'll be avoiding the "Tesla Solution" and sticking with the aftermarket. I did some more searching and it looks like I can buy a harness after all. Tekonsha makes one for the 2023 MY (linky). However, I had a terrible experience with a Tekonsha unit on my old BMW i3. It had issues despite being professionally installed rather than butchered by an amateur like myself so I'm leery of that brand now. It was so bad that the installer said he wanted nothing ever to do with my i3 or the Tekonsha brand again.

-Paul
 
Like I said, this is a last resort measure only. I want to retain my FSD 100% so I can use it if I want to while towing. Questions for you:

1. You said "Cruise Control is still available" - What exactly does this entail? Is it like the EAP I have in my other Tesla, or Autopilot like in my wife's tesla? If so, that would make going to the "Tesla Solution" more acceptable as I would still have self-adjusting speed control and lane centering, etc. Can you clarify? I want to make sure I don't end up with nothing, or just a fixed speed primitive cruise control.

So it sounds like there is NOT a plug anywhere on the Model Y for trailers unless one is added? How do I get this part if i were to install an aftermarket hitch? Can I order it from Tesla? Or do aftermarket companies make this harness?

-Paul
Towing with FSD sounds like a horrific idea.
 
My wife has a 2021 MY
Towing mode enables automatically when I put my bike rack and plug in the light.
I can disable it if I want to each time I drive with this setup.
FSD is not enabled on towing Mode, I think it becomes available once the towing mode is disabled.
BUT TBH I would advise against using FSD with a trailer attached. The system is still breaking like crazy sometimes for phantoms that are not there. Too risky to have whatever you are towing come full speed ahead against your car.
Get the Tesla option. Is the best solution of you are willing to spend the $$$
 
I have FSD Beta and the factory tow setup. I don't see how FSD could possibly work with any tow hitch pulling a trailer. The trailer is like having a second car back behind you. Lane changes require more room. Turning requires more room. Braking is different if the trailer weighs much at all. Trying to get FSD Beta to do all that when it is trained for driving only a car that is much shorter will sooner or later not end well, if you could even get the software to drive and ignore what it sees in the rear camera, which I don't think you will be able to do.

Get the factory hitch installed. It will be a long time, if ever, before passenger car self-driving packages graduate to being able to pull a trailer.
 
My wife has a 2021 MY
Towing mode enables automatically when I put my bike rack and plug in the light.
I can disable it if I want to each time I drive with this setup.
FSD is not enabled on towing Mode, I think it becomes available once the towing mode is disabled.
BUT TBH I would advise against using FSD with a trailer attached. The system is still breaking like crazy sometimes for phantoms that are not there. Too risky to have whatever you are towing come full speed ahead against your car.
Get the Tesla option. Is the best solution of you are willing to spend the $$$
I'm considering getting a cheaper bolt on hitch for closer to $300. But it would only be for accessories like small platform or bikes. I will have a bigger vehicle for trailers. If I were pulling trailers I'd get the Tesla setup.
 
I can disable it if I want to each time I drive with this setup.
FSD is not enabled on towing Mode, I think it becomes available once the towing mode is disabled.
Can somebody confirm that turning on and off tow mode while towing is indeed optional? And that once it is turned off even while hooked up, FSD access is restored? That would make me MUCH more willing to go with a Tesla Install despite costing 4x-5x more. To turn on and off tow mode with while hooked up, do you have to be stopped, or parked first? Or can you turn it on and off on the fly?

Thank you,

Paul
 
Can somebody confirm that turning on and off tow mode while towing is indeed optional? And that once it is turned off even while hooked up, FSD access is restored? That would make me MUCH more willing to go with a Tesla Install despite costing 4x-5x more. To turn on and off tow mode with while hooked up, do you have to be stopped, or parked first? Or can you turn it on and off on the fly?

Thank you,

Paul

To turn FSD back on, you go in and turn trailer mode off, I think that it is about 3-4 clicks to do. I am pretty sure that you can't enable when a trailer is attached. As other have said, it's not really safe to do.

FSD just doesn't understand the dynamics of towing. As has been said, something like phantom stops could be deadly. Have you ever been on the road and a large truck passes you and causes the trailer to push the car out the lane?

What about something as simple as making a turn? FSD doesn't know that it need to make a wide turn.

And as far as I know, the third party hitch is going to cause the car to go into the trailer mode as well. It's not the hitch that does it, it's the electrical connection. The cars senses the extra current.
 
To turn FSD back on, you go in and turn trailer mode off, I think that it is about 3-4 clicks to do. I am pretty sure that you can't enable when a trailer is attached. As other have said, it's not really safe to do.

FSD just doesn't understand the dynamics of towing. As has been said, something like phantom stops could be deadly. Have you ever been on the road and a large truck passes you and causes the trailer to push the car out the lane?

What about something as simple as making a turn? FSD doesn't know that it need to make a wide turn.

And as far as I know, the third party hitch is going to cause the car to go into the trailer mode as well. It's not the hitch that does it, it's the electrical connection. The cars senses the extra current.

I guess in theory you could wire trailer lights with a different module straight from the 12v (16v) battery connections and not the factory tow harness connection so the Tesla doesn't sense the current.

But none of these ideas sound safe at all. I guess if someone wanted to just test what FSD looked like on a very empty rural deserted stretch of open road then fine. But having this functioning in traffic with a vehicle towing thats not really designed to tow just sounds terrible and something I could see ending in a big negligence lawsuit or much worse.
 
I guess in theory you could wire trailer lights with a different module straight from the 12v (16v) battery connections and not the factory tow harness connection so the Tesla doesn't sense the current.

But none of these ideas sound safe at all. I guess if someone wanted to just test what FSD looked like on a very empty rural deserted stretch of open road then fine. But having this functioning in traffic with a vehicle towing thats not really designed to tow just sounds terrible and something I could see ending in a big negligence lawsuit or much worse.
uh, no?

Trailer lights are brake, turn, reverse and emergency. Hooking to 12V just leaves them all on.

But again, FSD gets pissed off with many bike racks, nothing attached to the power.
 
uh, no?

Trailer lights are brake, turn, reverse and emergency. Hooking to 12V just leaves them all on.

But again, FSD gets pissed off with many bike racks, nothing attached to the power.
When I said module I meant something like the below from etrailers that reads your factory brake lights, has power from 12v source, and sends correct signal to trailer. I didn't mean just wire trailer lights permanently to 12v.

 
I'm not looking to discuss the safety or merits of using FSD/EAP/AP while towing but since that's what this thread has mostly turned into I'll touch on a couple of things:

1. There's no way I would trust FSD to take turns, change lanes, or follow a point A to point B route. I want to use it for legs of my tow route where it's a relatively low speed divided highway that meanders for a while. Still trying to find out without any doubt whether I can turn trailer mode on and off in order to access FSD when I might want to utilize it while hooked up. So far one person says he belives yes, another person says he's pretty sure no. Anybody know for 100 percent certanity? Any video or photographic evidence out there? I started looking but am coming up short. I can try going by the Tesla store later today to ask in person but am not confident they will know what they're talking about based on my previous interactions with them.

2. I have been towing all my life without using any fancy "trailer mode" assistance. One of my side jobs (public teachers don't make enough in Hawaii) includes regularly towing trailers. I am comfortable towing all sorts of trailers using different vehicles. I would be using this to tow a little runabout style 14' boat, or a friend's PWC at the most.

Now can we please get this thread back on track?

1. Confirmation that if I have Tesla install the hitch and wiring, I still can turn off Trailer Mode to access FSD or at least basic AP while towing if so desired?

2. If no, what are the wiring options like from the aftermarket (or even from Tesla themselves if it will NOT block me from FSD)? I had a bad experience with the Tekonsha brand.

-Paul